Manufacture of fiber-reinforced,bitumen-containing products

ABSTRACT

A process for producing fiber-reinforced, bitumen-containing products which comprises reinforcing a bitumen-containing material with a fibrous material comprised of synthetic linear polycondensation products and substantially enhancing the adhesion between the fibrous material and the bitumen with the presence of an auxiliary substance comprising a resinous material that has a softening point between 50* and 160* C., is miscible with bitumen, and in the molten condition, acts as a wetting agent on the fibrous material of the polycondensation products.

United States Patent lnventor Sigbert Samson Rozendaal, Gilderland, Netherlands Appl. No. 738,815 Filed June 21, 1968 Patented Sept. 21, 1971 Assignee American Enka Corporation Enka, N.C. Priority June 29, 1967 Netherlands 67 -09049 MANUFACTURE ()F F BER-REINFORCED, BlTUMEN-CONTAINING PRODUCTS 8 Claims, No Drawings US. Cl 156/181, 117/47, 117/168, 260/26, 260/28 Int. Cl B29h 9/04 Field of Search 260/26, 28;

ll7/l68,47; 15 /181 Primary Examiner-Hosea E. Taylor Assistant Examiner-William B. Parker Attumey-Albin F. Knight ABSTRACT: A process for producing fiber-reinforced, bitumen-containing products which comprises reinforcing a bitumen-containing material with a fibrous material comprised of synthetic linear polycondensation products and substantially enhancing the adhesion between the fibrous material and the bitumen with the presence of an auxiliary substance compris' ing a resinous material that has a softening point between 50 and 160 C., is miscible with bitumen, and in the molten condition, acts as a wetting agent on the fibrous material of the polycondensation products.

MANUFACTURE OF FIBER-REINFORCED, BITUMEN- CONTAINING PRODUCTS This invention relates to the manufacture of bituminous products reinforced with synthetic fibrous materials and particularly to a process for reinforcing bitumen-containing materials with synthetic fibrous materials by using certain auxiliary materials to substantially improve the adhesion between the bitumen and fibrous materials and to the reinforced products obtained thereby.

Processes for reinforcing bitumen-containing materials with fibrous materials are known. An important problem in such processes is that there must be obtained sufficient adhesion between the reinforcing material, e.g., a fabric, and the surrounding bitumen.

ln this regard, it has already been proposed to use auxiliary substances e.g., in the use of coconut fibers, light hydrocarbon fractions, solar oil or fuel oil, have been suggested.

It has now been found that this adhesion may be considerably improved, particularly when the reinforcing materials used are fibrillary products containing synthetic linear polycondensation products, by using a very special auxiliary substance or material which is essentially different from the auxiliary substances heretofore used to promote adhesion of the fibrous reinforcing material to the bitumen.

This invention therefore contemplates a process for producing fiber-reinforced bitumen-containing products in which bitumen-containing materials, e.g., layers, plates, coatings, and the like masses, are reinforced with fibrous materials containing synthetic linear polycondensation products, and the adhesion between the bitumen and the fibrous materials waxes e.g., enhanced by the presence of an auxiliary substance comprising a resinous material that has a softening point between 50 and 160 C., is miscible with bitumen, and in the the above-noted condition, acts as a wetting agent on the fibrous materials of the polycondensation products.

More particularly, this invention is directed to a process for reinforcing bitumen-containing materials by contacting a fibrous reinforcing material containing synthetic linear polycondensation products with a heated, flowable bitumencontaining material, by solidifying the bitumen onto the fibrous material, and by providing, as the auxiliary substance an acid-type resin derived from coniferous wood, such as tall resin, on the contact surfaces between the fibrous reinforcing material and the bitumen at the moment the bitumen solidifies.

Also, this invention is concerned with the fiber-reinforced, bitumen-containing product obtained by the above-described processes. This product comprises a bitumen-containing material adhesively bonded to a synthetic fibrous reinforcing material in the presence of a resin, e.g., tall resin, that exhibits the heretofore described properties necessary for insuring improved adhesion between the fibrous material and the bitumen.

It will be understood that the term bitumen as used herein includes products which in the English technical literature are officially referred to as asphaltic bitumen" or bitumen as defined on page 549 of The Petroleum Handbook published in 1948 by The Shell Petroleum Company, Limited. Thus, bitumen" includes asphaltlike hydrocarbons such as asphalt, asphaltites, asphaltic pyrobitumens, mineral tars, mineral waxes e.g., ozokerite and the like, which may be hard and brittle, or semisolid substances. Also, the terms asphalt or asphaltic as used herein are to include the meaning set forth on the above-noted page 5 49 of The Petroleum Handbook.

It will be appreciated that the products obtained by this invention include those bituminous structures having one or more layers, coatings, coverings, sheets and the like bitumencontaining materials which are bonded to a substrate of a bitumen base material in which a fibrous material, e.g., a synthetic fibrillary product, forms a reinforcement for the layer of bitumen or for the bitumen base material or for both. it will be understood that the bitumen base material is meant to encompass those materials having bitumen as a base for other substances, including aggregates, fillers and the like.

It will also be understood that the bitumen layer used to produce the reinforced products of this invention may further be mixed with organic materials such as wood flour, cork flour and the like, and may also include inorganic fillers having a particle size smaller than about 200 mesh.

The linear polycondensation products suitable for purposes of this invention include fiber-forming materials such as the polyamides prepared from lactams, e.g., caprolactam, and the polyamides prepared from diamines and dicarboxylic acids, e.g., hcxamethylene diamine and adipic acid, the polyesters prepared from terephthalic acid or the ester-forming derivatives thereof, and glycols, e.g., polyethylene terephthalate and the like, Also, it will be understood that the terms polyamides and polyesters include not only. homopolymers, but also copolymers.

It will be appreciated that other synthetic fiber-forming materials such as polyacrylonitrile, copolymers of acrylonitrile and the like may also be used to form the reinforcing fibrous materials.

The fibrous materials useful as reinforcing materials include twisted or untwisted continuous multifilament yarns, monofilaments, spun yarns, threads and staple fibers. ln the process according to the invention, the fibrous material may be used in a loose form, more particularly in the form of individual fibers. When such fibers are used, they may be mixed with the bitumen or asphalt before the mass is made into a coating or covering layer; for instance, on roads or dykes, tile plates and the like. Threads and fibers may be used in the form of woven or knitted fabrics or bonded or nonbonded fiber sheets; preferably, woven fabrics made from continuous filament yarns are used.

It will be appreciated that the fibrous materials, e.g., threads and fibers, used as reinforcing materials may consist entirely of synthetic linear polycondensation products such as polyamides and/or polyesters, or be mixed with threads and like fibrous materials made from a different material, for instance, glass, cotton or regenerated cellulose.

When woven or knitted textile products are used, the nature of the product to be reinforced determines the denier of the yarn to be applied and the density of the yarns in the textile product.

For the purpose of reinforcing an asphalt mass with the aid of woven fabrics, it is preferred to use multifilament yarns based on synthetic linear polycondensation products and having a relatively high denier (for instance, 1,000 or higher), and a filament denier of 3 or more. If desired, the yarns to be used may be composed of yarns of a lower denier which are twisted together.

In order to improve the adhesion between the woven or knitted fabrics and the asphaltor bitumen-containing mass, it is preferred to use wide-meshed textile fabrics. Exam les of such fabrics are woven fabrics containing four weft threads and four warp threads per centimeter. Woven fabrics have an advantage over knitted fabrics in that they can more readily be kept under a pretension while being incorporated in the asphalt mass. Such pretensioning reduces the risk of the formation of cracks in reinforced coatings, covering layers or tile plates. It has further been found that the best results in such cases are obtained when the fabrics used are composed of threads having a relatively low elongation.

For the purpose of reinforcing bitumen layers used on a large scale, as for roofing, it is preferred to use more densely woven fabrics.

The addition of the auxiliary substance to obtain improvement of the adhesion between the fibrous material and the bitumen may be carried out in various ways. It is essential that the moment the bitumen or the asphaltsolidifies, the auxiliary substance, e.g., tall resin, should be present on the contact surfaces between the fibrous materials, e.g., threads, and the bitumen-containing substance or mixture of substances.

In principle, this may be achieved by various methods; for instance, by adding the resin to the bitumen or to the asphalt mass or by first coating the reinforcing threads with the resin.

The last-mentioned method leads to particularly satisfactory adhesion and is more economical as far as the required amount of the resin is concerned. According to this invention, it has been found that an acid-type resin derived from coniferous wood such as tall resin, is particularly effective as an auxiliary material for increasing the adhesion between a bitumen-containing layer or base material and the synthetic fibrous reinforcing material. The resin must be of the type that is miscible with bitumen, has a softening point between 50 and 160 C. and will act, in the molten condition, as a wetting agent on threads of the synthetic polycondensation products. In this manner, the resin promotes the flow of the bitumen into intimate contact with the fibrous reinforcing material whereby the adhesion therebetween is substantially improved, i.e., increased.

In accordance with this invention, the tall resin used is the resin acid fraction of tall oil. This resin may be extracted from tall oil by fractional distillation. Tall oil itself is a byproduct in the preparation of sulfate pulp from pine wood.

The term tall resin" as used herein is also meant to include tall resin mixtures which still retain the adhesion-improving effeet of the tall resin. In general, such mixtures contain percent by weight or more of the tall resin. This percentage is highly dependent on the nature of the mixture. When bitumen is used to form the mixture the tall resin will in general have to be used in the mixture in an amount of more than 50 percent by weight.

The physical and chemical properties as well as the composition of tall resin slightly vary with the source. In general, its softening point is about 73C.

It appears that in the processing of hot asphalt, which takes place at temperatures higher than 100 C., the tall resin improves the flow of the asphalt at the surface of the reinforcing material. This flow fully disappears when the mass is cooled down to below 70 C. Apparently, this flow improves impregnation of the reinforcing material with the asphalt, so that a better adhesion is obtained. Surprisingly and unaccountably, the adhesion of the asphalt to the synthetic linear polycondensation products is particularly improved.

In order to obtain optimum adhesion, it is desirable that an amount of unmixed tall resin should be provided on the reinforcing fibrous material, e.g., threads. The unmixed tall resin is preferably used in an amount of at least 30 percent, calculated on the weight of the threads. Provision of the resin on the threads may best be carried out by impregnating or spraying the threads with a solution or dispersion; for instance, an aqueous dispersion of the tall resin.

Suitable solvents for the tall resin are trichloroethylene and perchloroethylene.

In order that the resin solution may be sufficiently fluid, it is preferred to use solutions of tall resin in trichloroethylene which contain one part by weighty of trichloroethylene to one part by weight of tall resin.

Such solutions have a sufficiently high viscosity to insure that under the usual operating conditions, the required amount of resin is applied to the fibrous materials.

The application of the resin to the fibrous material, e.g., threads, may take place in various processing stages, namely before or after being processed into woven fabrics, in which form the reinforcing threads are (as mentioned before) preferably used.

After the resin has been applied to the threads, the solvent or dispersant must be removed, for instance, by evaporation.

The solvent, which is preferably trichloroethylene, may be removed completely, but preferably the drying process is so carried out that a few percent of the solvent is left in the resin. This prevents brittleness and stops the resin from cracking off the threads.

Instead of by impregnation, it may be insured that the surface of the fibrous material carries a sufficient amount of tall resin at the moment of bonding by sprinkling the fibrous material with the resin. For example, reinforcing threads may be sprinkled with the pure tall resin or with a mineral carrier to which the resin is applied by impregnation or coating.

With the last mentioned method, care must be taken to insure that the resin is uniformly distributed over the threads.

It will be appreciated that this particularly good adhesion obtained between threads or fibers of synthetic linear polycondensation products and asphalt or bitumen by the application of tall resin is of particular importance to various branches of the building industry.

In the manufacture of roofing material and construction panels, in which synthetic thread-shaped material has been previously used as reinforcements, the use of all resin leads to a considerable improvement in the product strength.

This use is an even greater advantage in road building. In road surfaces, cracks are formed in many places owing to a soft sublayer or the slope of the road surface. Such cracks cause accelerated wear. The incorporation of fabrics may in this respect have a favorable influence, but owing to the insufficient adhesion between threads and asphalt, optimum results have not yet been obtained. The use of tall resin considerably improves this adhesion.

The invention will be further described in the following examples which are merely illustrative and are not intended to be restrictive of the scope of the invention.

EXAMPLE 1 Bitumen having a penetration value of 67 (7.25 percent by weight) was mixed at 170:5 C. with 45 percent by weight of road metal 2/5, 39.75 percent by weight of sand and 8 percent by weight of a medium-grade filler, the percentages by weight being based on the total admixture. Of the sand, 20 percent passed through a screen of 2.4 mm. mesh-width, but was retained by a screen of 0.42 mm. mesh-width, 45 percent passed through the screen of 0.42 mm. mesh-width, but was retained by a screen of 0.l mm. mesh-width, and 35 percent passed through the last-mentioned screen, but was retained by a screen of 0.075 mm. All of the tiller passed through a screen of 0.075 mm.

At l45:t5 C., nine l,400-gram portions of the bitumencontaining admixture were pressed to tiles measuring l5 30 cm. and having rounded corners.

After the tiles had been colled, three of them were uniformly sprinkled with 5.5 grams of tall resin, and another three with the same amount of montan resin (the resin contained in montan wax which may be separated by extraction). To the remaining three tiles was applied an asphalt varnish commonly used as an adhesive in the road building industry. The asphalt varnish was provided on the tiles in such an amount that 7 grams of solid material was left on the tile.

The properties of the tall resin used were:

Softening point 73.5 C. Saponificatiun number l74 Acid number 158 Resin acid content 81% Content of unsaponifiable material 5.5%

The properties of the montan resin used were:

solidifying point IS-76 C. Acid number 3040 Saponificution number 55*65 Subsequently, polyethylene terephthalate yarns were, at 2.5 cm. intervals, stretched over the tiles in a direction transverse to the length thereof.

Each of the yarns had been obtained by twisting together at 45 turns Z per meter three 1,000 denier polyethylene terephthalate yarns made up of l92 filaments and having a singles twist of 70 turns S per meter.

A top layer made by the same asphalt mass as described above was pressed on to the yarns and the tiles at l45 15C. For this purpose, use was made of 2,100 grams of asphalt per tile. Compression was so carried out that the tile contained not more than 1 percent empty space.

The tiles thus obtained were cooled down, after which 4 cm. were sawed off at the sides transverse to the direction of the yarn.

The sawed blocks were mounted in an Instron tensile tester of the type C.R.E. (Constant Rate of Elongation), after which a tensile force was applied to the thread ends. The rate of pulling was 2 cm. per minute.

The maximum tension reached in the thread ends was measured. This maximum tension is a measure of the adhesion of the yarns to the asphalt.

With the tiles manufactured with the aid of tall resin, the maximum values, after 40 tensile tests, were between 14 and 18 kg.

With the montan resin tiles, the maximum yarn tensions were between 8 and 9 kg.

With the tiles manufactured with the aid of the asphalt varnish, the maximum yarn tensions were between 4 and 5 kg.

EXAMPLE ll in the manufacture of a reinforced road surface based on asphalt, there was formed on a sublayer of mechanically compacted sand a foundation layer, which was rolled to a thickness of 7 cm. In preparing the foundation layer, use was made of a mixture of gravel, sand, a low-grade filler and asphalt bitumen 80/100. The mineral mixture in the asphalt was composed as follows:

50 percent by weight passed through a screen of 32 mm. mesh-width, but was retained by a screen of 2.4 mm. meshwidth;

40 percent by weight passed through the screen of 2.4 mm. mesh-width, but was retained by a screen of 0.075 mm. mesh-width; and

5 percent by weight passed through the screen of 0.075 mm.

mesh-width.

The amount of asphalt bitumen was 5.5 percent by weight of the mineral mixture.

On the foundation layer, an adhesive layer of an anionic 50 percent asphalt emulsion was provided, over which there was unrolled a fabric to which 40 percent by weight of tall resin (based on the weight of the fabric) had been applied.

The fabric, which was made essentially of polyethylene terephthalate, and was of the plain weave type, showed four weft threads and four warp threads per centimeter.

The weft and warp yarns each consisted of two draw-twisted 1,000-denier yarns (210 filaments) which had been twisted together to 70 turns Z. The residual shrinkage of the yarns was 8-9 percent. The fabric was stretched in the longitudinal and transverse directions and pinned down. An asphalt emulsion of the above-mentioned composition was sprayed onto the fabric, the amount of the asphalt emulsion provided on top of the fabric being twice as much as that present under the fabric.

After the asphalt emulsion had broken up, two asphalt layers, each 7 cm. thick, were successively provided on the foundation layer and rolled. For these two layers, the same asphalt mass was used as described above. The asphalt masses were worked up at a temperature of 145flC.

To these layers was subsequently applied the anionic 50 percent asphalt emulsion. After the emulsion had broken up, a binder layer 4 cm. thick was rolled on to these layers. This binder consisted of road metal, sand, a medium-grade filler and asphalt bitumen 80/ 100. Of the mineral mixture:

70 percent by weight passed through a screen of 16 mm. mesh-width, but was retained by a screen of 2.4 mm. mesh width;

25 percent by weight passed through the screen of 2.4 mm. mesh-width, but was retained by a screen of 0.075 mm. mesh-width; and

5 percent by weight passed through the screen of 0.075 mm.

meshwidth.

The amount of asphalt bitumen 80/100 was 5.5 percent by weight of the mineral mixture.

To the binder layer was applied an asphalt emulsion, which formed an adhesive layer, on which a second fabric was provided, which was identical with that described above and which was covered with a 50 percent asphalt emulsion.

After the emulsion had, after some time, automatically broken up, a top layer was applied, which was 4 cm. thick and consisted of road metal 5/ l5 and road metal 2/5, sand, a medium-grade filler and asphalt bitumen /100. Of the mineral mixture:

35 percent by weight passed through a screen of 16 mm. meshwidth, but was retained by a screen of 5.6 mm. mesh-width;

22 percent by weight passed through the screen of5.6 mm. meshwidth, but was retained by a screen of 2.4 mm. mesh-width;

35 percent by weight passed through the screen of 2.4 mm. mesh-width, but was retained by a screen of 0.075 mm. mesh-width; and

8 percent by weight passed through the screen of0.075 mm.

mesh-width.

The asphalt bitumen 80/100 was used in an amount of 7.2 percent by weight, calculated on the weight of the mineral mixture.

The asphalt was worked up at a temperature of l50i5 C.

The dimensional stability of this fabric reinforced road surface was substantially improved over surfaces prepared without the use of the tall resin impregnated reinforcing fabric.

in the construction of this road surface, use was made of two layers of fabric. However, it is also possible to use a larger or smaller number. They may be incorporated in the road sur face in different places, or the road surface may be built up on a fabric layer.

Advantageously, when the road surface is built up on the fabric, the vehicles bringing up the road materials may run over the fabric instead of the metal strips conventionally used. The adhesion between the fabric and the resin is sufficient to withstand the strain.

While the novel features of the invention have been shown and described and are pointed out in the appended claims, it is to be understood that various omissions, modifications and substitutions in the features shown and described may be made by those skilled in the art without departing from thc spirit and scope of the invention.

What is claimed is:

1. A process for producing fiber-reinforced, bitumen-containing products which comprises treating a fibrous material consisting essentially of fiber-forming synthetic linear polycondensation products selected from the group consisting of polyamides and polyesters, with a tall resin that is the resin acid fraction of tall oil, and that has a softening point between 50 and C., is miscible with bitumen and in the molten condition acts as a wetting agent on the fibrous material; and reinforcing a bitumen-containing material with the treated fibrous material, said tall resin substantially enhancing the adhesion between the reinforcing fibrous material and the bitumen in said bitumen-containing material.

2. The process of claim 1, in which the bitumen-containing material is reinforced by contacting the bitumen-containing material in a flowable and heated condition with the treated fibrous material, and then solidifying the bitumen-containing material while in contact with the fibrous material.

3. The process of claim 1 in which the reinforcing fibrous material is made of polyethylene terephthalate.

4. The process of claim 1 in which the reinforcing fibrous material is used in the woven state.

5. The process of claim 1 in which the reinforcing fibrous material is coated with the. tall resin.

6. The process of claim 5 in which the reinforcing fibrous material is coated with tall resin in an amount of at least 30 percent, calculated on the weight of the fibrous material.

7. The process of claim 5 in which the reinforcing fibrous material is coated with a solution of tall resin in trichloroethylene and is subsequently dried.

8. A fiber-reinforced bitumen-containing product obtained from the process of claim 1. 

2. The process of claim 1, in which the bitumen-containing material is reinforced by contacting the bitumen-containing material in a flowable and heated condition with the treated fibrous material, and then solidifying the bitumen-containing material while in contact with the fibrous material.
 3. The process of claim 1 in which the reinforcing fibrous material is made of polyethylene terephthalate.
 4. The process of claim 1 in which the reinforcing fibrous material is used in the woven state.
 5. The process of claim 1 in which the reinforcing fibrous material is coated with the tall resin.
 6. The process of claim 5 in which the reinforcing fibrous material is coated with tall resin in an amount of at least 30 percent, calculated on the weight of the fibrous material.
 7. The process of claim 5 in which the reinforcing fibrous material is coated with a solution of tall resin in trichloroethylene and is subsequently dried.
 8. A fiber-reinforced bitumen-containing product obtained from the process of claim
 1. 